Atrial fibrillation is a heart condition whereby abnormal electrical signals cause irregular heart contractions. One treatment for this condition includes open heart surgery and creating several lesions in the endocardium of the atria. These lesions can function to block aberrant electrical impulses, permitting an impulse originating from the sinus node to properly regulate heart contraction. However, because open heart surgery is highly invasive and requires a lengthy patient recovery period, alternate methods for making lesions are required. One alternative procedure uses ablation catheters.
Typically, an ablation catheter is advanced into the heart via the patient's blood vessels. When the catheter's electrodes are placed in the desired position within the heart chamber, radio frequency (“RF”) energy is supplied to the catheter. Such RF energy ablates the tissue surrounding the ablation electrode, thereby creating a lesion in the endocardium.
Traditional ablation catheters included an elongated shaft with an ablation electrode mounted at the distal end of the shaft. Point or linear lesions could be formed with these catheters by manipulating the placement of the distal tip. However, creating suitable lesions using these catheters can be difficult because the tip electrode may overheat during ablation. Newer catheter designs mitigated these disadvantages by cooling the tip electrode during use, thereby minimizing the risk of overheating.
However cooled ablation catheters are limited in their ability to accurately determine the temperature of tissue surrounding the tip electrode. Temperature sensors of such catheters typically sense the temperature of the cooling fluid rather than tissue temperature. Accurate tissue temperature readings are desirable as they can provide a useful indication of tissue ablation. Accordingly, the present disclosure provides devices and methods for accurately determining tissue temperature that overcomes some of the disadvantages of current ablation technologies.